Fluids

1
Fluids Electrolytes
2
Body water and fluid volumes

• Water constitutes 50 to 70 of lean body weight
  .
• Total body water.
• intracellular fluid compartment (40 of body
  wt).
• Extracellular fluid compartment (20 of body
  wt).
• ? plasma 5 of body wt .
• ? An interstitial compartment 15
  of body wt.

3
Blood volume of an adult

• Blood volume of an adult is 5 L-7L OF normal body
  weight or 70 ml/ kg.
• Blood volume consists of plasma erythrocyte
  volumes.
• ? 70 kg man has a TBW of 42 L.
• ? ECF is 1/3 TBW ( 14 L ).
• ? Plasma 1/4 (5) ECF ( 3.5 L ).
• ? Hematocrit of 40 gtgtgt 1.5 L RBC volume
• gtgtgtgt 3.5L 1.5L 5L

4
Ions and osmolality

• K Mg are the major IC cations.
• Na is the major EC cation.
• Balance between the EC and IC ions is maintained
  through the osmolality and active transporter
  Na/K ATP pump.
• ( if ATP depleted gtgtgt cellular dysfunction).
• Osmolality is the concentration of solute in the
  solution (determined by ionic conc. Of the
  dissolved substances per unit solvent).
• The normal blood osmolality is 300 mosm.
• Osmolality 2Na glucose BUN 300_15.

5
Ions and osmolality

• What is the main regulator of osmolality?
• ADH
• - As osmolality gt 300 mosm , osmoreceptor
  cells in the supra- optic nuclei of the
  hypothalamus signal the posterior hypothalamus to
  increase production of ADH.
• - ADH increases water absorption from distal
  renal tubules.

6
Fluid electrolyte requirements

• The approximate daily fluid requirements for an
  individual is based on body weight at room
  temperature
• The 1st 10 kg gtgtgt 100 ml/kg/day
• 4
  ml/kg/hr
• The 2nd 10 kg gtgtgt 50 ml/kg/day
• 2
  ml/kg/hr
• Wt. above 20kg gtgtgt 20 ml/kg/day
• 1
  ml/kg/hr

7
Fluid electrolyte requirements

• How much fluid would an average adult (70kg) need
  in a day?
• 2500 ml
• ( 1000 ml 500 ml 1000 ml )gtgtgtgtnormal
  saline

8
Fluid electrolyte requirements

• The approximate daily electrolytes requirement
  is as follows
• Na, K, Cl- gtgtgtgt 1 mEq/kg/day each
• Ca gtgtgtgt 2 g/day
• Mg gtgtgtgt 20 mEq/day
• N.B neither Ca nor Mg is necessary in
  maintenance IV fluid.

9
Fluid electrolyte requirements

• Sources of insensible fluid loss in a healthy
  adult are
• - Respiratory gtgt 600ml/day
• - Skin gtgt 400ml/day
• ( In fever, insensible skin loss can increase up
  to 250 ml/day/degree of fever ).
• - Stool gtgt 200 ml/day

10
Evaluation of intravascular volume

• Intravascular volume can be assessed using
  history ( heat expoure - vomiting diarrhea)
  physical examination or lab. Examinations.
• 1- Physical examination ( Signs)
• Hypovolemia
• skin turgor
• hydration of mucous membranes
• palpation of peripheral pulses
• resting heart rate
• BP and their orthostatic changes
• urine output
• Hypervolemia
• pitting edema
• increased urinary output
• signs of pulmonary edema

11
Evaluation of intravascular volume

• 2- Lab. Investigations
• Hypovolemia
• rising hematocrit.
• metabolic acidosis.
• urine specific gravity gt1.010.
• urine sodium lt10 mEq/L.
• urine osmolality gt 450 mOsm/kg.
• hypernatraemia.
• BUN / creatinine gt 101.
• Hepervolemia
• radiographic signs of increased pulmonary
  vascular and interstitial markings Kerly B
  lines or diffuse alveolar infiltrates).

12
Evaluation of intravascular volume

• 3- Hemodynamic measurements
• A. CVP ( indicated when volume status is
  difficult to assess or when rapid or major
  alterations are expected).
• Hypovolemia CVP lt 5 mm Hg, small elevation (
  1- 2 mm in response to 250 ml fluid bolus ).
• Hypervolemia CVP gt 12 mm Hg (in the
  absence of Rt ventricular dys- function,
  increased intrathoracic pressure, restrictive
  pericardial).
• B. Pulmonary artery pressure.

13
Intravenous Fluids

• IV fluid therapy may consist of infusions of
  crystalloids, colloids, or a combination of both.
• Crystalloids
• Aqueous solutions of LMW salts with or without
  glucose.
• They rapidly equilibrate with and distribute
  throughout the ECF space.
• Colloids
• contain high MW substances such as proteins or
  large glucose polymer.
• They maintain plasma oncotic pressure and remain
  mainly intravascularly.

14
Intravenous Fluids

• General principles
• 1- Crystalloids when given in
  sufficient amounts can be just as effective
  as colloids in restoring intravascular volume.
• 2- Replacing an intravascular volume
  deficit with crystalloids generally
  require 4 X the volume needed using colloid

15
Intravenous Fluids

• General principles
• 3- Most surgical patients have an ECF
  deficit that exceeds the ICF deficit.
• 4- Severe intravascular fluid deficits
  can be more rapidly corrected using colloid
  solutions.
• 5- The rapid administration of large
  amounts of crystalloids (gt 4-5 L ) is more
• frequently associated with significant tissue
  edema.
• ( marked tissue edema can impair oxygen
  transport, tissue healing and return of bowel
  Function following major surgery ).

16
Intravenous Fluids

• 1- Crystalloid solutions
• Includes a wide variety of solutions.
• Intravascular half life is 20 30 minutes.
• Solutions are chosen according to the type of
  fluid loss
• Maintenance solutions.
• ( Hypotonic solutions in
  cases of primarily water deficit).
• Replacement solutions.
• ( Isotonic solutions in
  cases of both water and electrolyte deficits).
• 
  
• N.B Glucose is provided in some solutions to
  maintain tonicity or to prevent ketosis and
  hypoglycemia due to fasting. ( Children and women
  more prone to hypogly.).

17
Intravenous Fluids

• Crystalloids
• Since most intraoperative fluid losses are
  isotonic, replacement type solutions are
  generally used.
• The most commonly used fluid is lactated Ringers
  solution
• - slightly hypotonic and tends to
  lower serum Na to 130 mEq/L.
• - Generally it has the least effect on
  ECF composition, and it is the
• most physiologic solution when
  large volumes are needed.
• - Lactate is converted by the liver
  into bicarbonate.

18
Intravenous Fluids

• Crystalloids
• Normal Saline
• - When given in large volumes, it
  produces dilutional hyperchloremic
  acidosis bec. Of its high Na Cl- contents (
  Plasma bicarbonate conc. decreases as Cl- conc.
  Increases).
• - Thus, NS is a preffered solution
  in for hypochloremic metabolic alkalosis and for
  diluting PRBCs prior to transfusion.

19
Intravenous Fluids

• Crystalloids
• D5W
• - Used for replacement of pure water
  deficits and as a maintenance fluid for patients
  on sodium restriction.
• Hypertonic 3 saline
• - Treatment of severe symptomatic
  hyponatremia.
• NB 3 - 7.5 saline solutions are used in
  resuscitation of patients in hypovolemic shock
  (they must be administered slowly , preferably
  through CVP, bec they readily cause hemolysis).

20
Intravenous Fluids

• 2- Colloid solutions
• Intravascular half life 3 6 hours (because the
  osmotic activity of its high MW substances tends
  to maintain it intravascularly).
• The substantial cost and occasional complications
  tend to limit their use.
• Generally accepted indications for use
• Severe intravascular fluid deficits ( hemorrhagic
  shock) prior to arrival of blood for transfusion.
• Severe hypoalbuminaemia or conditions associated
  with large protein losses such as burns.

21
Intravenous Fluids

• Colloids
• Several colloid solutions are generally
  available.
• They are derived from either plasma proteins or
  synthetic glucose polymers, and they are supplied
  in isotonic electrolyte solutions.

22
Intravenous Fluids

• Colloids
• Blood derived colloids
• - includes albumin (5 and 25
  solutions) and plasma
• protein fraction (5).
• - Both are heated to minimize the risk
  of hepatitis and
• other virally transmitted diseases.
• - Plasma protein fraction is associated
  with hypotensive
• reactions ( allergic).

23
Intravenous Fluids

• Colloids
• Synthetic colloids
• - include dextrose starch and gelatins.
• ( gelatins are associated with
  histamin mediated allergic reactions
• and are not available in the USA).
• - Dextrose starches include Dextran
  and Hetastarch.
• 1- Dextran is available as dextran 70 and
  Dextran 40. When infused in a rate more than
  20ml/kg/d, they will be associated with certain
  complications.

24
Intravenous Fluids

• Colloids
• Complications associated with Dextrans
• - Interfering with blood typing.
• - Prolong bleeding time ( antiplatelets
  effect).
• - Renal failure.
• - Anaphylactic reactions ( mild severe).

25
Intravenous Fluids

• Colloids
• 2- Hetastarch is highly effective as a plasma
  expander and less expensive than albumin.
• - It is non antigenic ( thus anaphylactic
  reactions are rare).
• - Coagulation and bleeding times not
  significantly affected.
• Pentastarch ( LMW starch solution, is less
  likely to cause adverse effects and may replace
  hetastarch.

26
Acute electrolyte imbalance

• Disorders of Sodium balance.
• Disorders of Potassium balance.
• Disorders of Calcium balance.
• Disorders of Phosphorus balance.
• Disorders of Magnesium balance.

27
Disorders of Sodium balance

• Physiology
• The normal individual consumes 3-5g/day NaCl.
• Balance is maintained primarily by the kidneys.
• Normal Na concentration is 135-145 mmol/l .
• Potential sources of significant Na loss included
  sweat ,urine and gastrointestinal secretions.
• N.B. Na concentration and total body water are
  controlled by independent mechanism, As a
  consequence hypo and hypernatremia may occur in
  conjugation with hypovolemia, hypervolemia or
  euvolemia, thus it is necessary to measure the
  osmolality to evaluate the patient with
  hyponatremia.
• Na concentration largely determines the plasma
  osmolality (Posm) which can be approximated by
  the following equation.

28
Disorders of Sodium balance

• Na concentration largely determines the plasma
  osmolality (Posm) which can be approximated by
  the following equation

29
hyponatremia

• Hyponatremia
• Low serum Na lt135.
• Due to - Loss of Na .
• - Gain of H2O.
• Main regulation of the Na ? extracellular
  osmolality ---?hypothalamus
• Nausea ? ADH ? low Na /K
• Cause of ADH
• - hypernatremia
• -
  hypovolemia
• - brain
  occupied lesion
• - truma
• - drug
  acting centrally ? morphine pethidine
  NASID - Li
• - pain
• - nausea ,
  vomiting
• - SIADH low plasma osmolality (lt280
  mOsm/L),Hyponatremia (lt135mmol/L),low urine
  output with concentrated urine (gt100
  mOsm/kg),elevated urine sodium (gt20mEq/l),
  clinical euvolemia

30
Disorders of Sodium balance

• Hyponatremia
• Causes and diagnosis
• Hyponatremia may occur in conjunction with
  hyper tonicity ,isotonicity or hypo tonicity so
  it is necessary to measure the serum osmolility
  to evaluated patients with hyponatremia.
• Isotonic hyponatremia
• OSMOLILITY 280-290 mOsm
• Note measure blood glucose ,lipid , protein
• Pseudohyponatremia
• Hyperlipidemia
• Hyperproteinemia
• Isotonic infusions
• Glucose
• Mannitol
• Glycine
• TURP

31
Disorders of balance Sodium

• 2- Hypertonic hyponatremia (gt290 mOsm )
• Note measure blood glucose .
• Causes
• Hyperglycemia
• Hypertonic infusions
• Glucose
• Mannitol
• glycine
• TURP
• hyponatremia in conjunction with cardiovascular
  and neurological manifestation , which
  infrequently follow transurethral resection of
  prostate Results from intraoperative absorption
  of significance amounts of irrigation of fluid
  (glycerine, sorbitol, mannitol) may occur in
  isotonic ,hypotonic , hypertonic hyponatremia

32
Disorders of Sodium balance

• 3- hypotonic hyonatremia (lt280 mOsm)
• Is classified on basis of extracellular fluid
  volume Generally developed as a consequence of
  the administration and retention of hypotonic
  fluids dextrose 5 in water ,0.45 Nacl .
• 1. Hypovolemic hypotonic hyponatremia
• In the surgical patient most commonly
  results from replacement of sodium rich fluid
  losses (from the GI tract, skin or lungs)with
  an insufficient volume of hypotonic fluid .
• GI losses
• Skin losses
• Lung losses
• Third space losses
• Renal losses

33
Disorders of Sodium balance

• 2. Hypervolemic hypotonic hyponatremia
• The edematous states of congestive heart failure
  , liver disease , nephrosis occur in conjunction
  with inadequate circulating blood volume renal
  retention renal retention of sodium and water
  disproportionate accumulation of water
  hyponatremia

34
Disorders of balance Sodium

• 3. Isovolemic hypotonic hyponatremia
• Water intoxication
• K losses
• Reset osmostat
• SIADH low plasma osmolality (lt280
  mOsm/L),Hyponatremia (lt135mmol/L),low urine
  output with concentrated urine (gt100
  mOsm/kg),elevated urine sodium (gt20mEq/l),
  clinical euvolemia
• Drugs sulfonylureas carbamazepine
  phenothiazines -antidepressnts

35
Disorders of Sodium balance

• Clinical manifestation
• Symptoms associated with hyponatremia are
  predominantly neurological .
• Posm
  intracellular water influx
• intracellular volume
  cerebral edema
• Mild to moderate hyponatremia ( Na gt 125 mEq/L
  ) Asymptomatic.
• Early symptoms gtgtgt Non specific anorexia,
  nausea, weakness.
• Severe hyponatremia ( Na lt 120 mEq/L) gtgtgt
  lethargy, confusion, seizures, coma, death.

36
Disorders of Sodium balance treatment

• Isotonic and hypertonic hyponatremia Correct
  with resolution of under lying disorder.
• Hypovolmic hyponatremia administration of 0.9
  NaCL to correct volume deficits and replace
  ongoing losses .
• Water intoxication fluid restriction
  (1000ml/day)
• SIADH water restriction (1000ml/day)initially
  ,then a loop diuretic (furosemide ) or an osmotic
  diuretic (mannitol ).

37
Disorders of Sodium balance treatment

• Hypervolmic hyponatremia
• Water restriction to return Na to greater than
  130 mmol /L.
• Optimizing cardiac performance in case of severe
  congestive heart failure.
• If the edematous hyponatremic patient becomes
  symptomatic plasma NA can be Increased to safe
  level by the use of a loop diuretic ( furosemide
  ,20-200mg IV every 6 hr )and replacing urinary
  Na losses with 3 Nacl ,reasonable approach is
  to replace approximately 25of the hourly urine
  output with Nacl ,hypertonic saline should not be
  administration to these patients without
  Concomitant diuretic therapy.
• Administration of synthetic brain natriuretic
  peptide (BNP) is also therapeutically in the
  setting of the acute heart failure because it
  inhibit Na reabsorption at the cortical
  collecting duct failure because it inhibits the
  action of vasopressin on water permeability at
  the inner medullary collecting duct.

38
Disorders of Sodium balance treatment

• In the presence of symptoms or extreme
  hyponatremia Nalt110mmol/L
• Hypertonic saline (3Nacl )is indicated to
  correct serum Na to 120mmol/L.
• The quantity of 3 Nacl that is required to
  increase serum Na to 120mmol/L can be estimated
  by calculating the Na deficit
• Na deficit (mmol)0.6xlean body weight
  (kg)x120-measured serum Na (mmol/L) .
• Central pontine demylination occurs in the
  setting of correction of hyponatremia , the risk
  factors for demyelination are contraversial but
  appear to be related to chronicity of
  hyponatremia (gt48hr) and the rate of correction .

39
Disorders of Sodium balance hypernatremia

• Hypernatremia
• Is uniformal hypertonic and typically the result
  of water loss in excess of solute .
• Patients are categorized on the basis of their
  extracellular fluid volume status

40
Disorders of Sodium balance hypernatremia

• Clinical manifestation Symptoms are primarily
  neurologic
• Lethargy.
• Weakness.
• Irritability .
• Fasciculations .
• Seizures.
• Coma.
• Irreversible neurologic damage .

41
Disorders of Sodium balance hypernatremia

• Diagnostic approach to hypernatremia
• Clinically assess ECF volume
• Depleted hypovolemic hypernatremia loss of
  water and sodium
• Renal (diuretics glycosuria urea diuresis
  acute and chronic renal failure partial
  obstruction )
• GI losses (diarrhea)
• Respiratory losses
• Skin losses (burns)
• Adrenal insufficiency

42
Disorders of Sodium balance hypernatremia

• 2. ECV normal isovolemic hypernatremia loss of
  water
• Diabetes insipidus
• Characterized by polyuria and polydipsia in
  association with hypotonic urine (urine
  osmolality lt200 mOsm/kg ) and high plasma
  osmolality (gt287mOsm/kg )
• Types of DI
• central diabetes insipidus(CDI)
• - a defect in the
  hypothalamic secretion of ADH .
• - head trauma ,
  intracranial tumors , infections, vascular
  disorders
• (aneurysms ) , hypoxia ,
  medications(clonidine ,phencyclidine ).
• nephrogenic diabetes insipidus (NDI)
• -renal insensitivity
  to normally secrection ADH
• -familial, drug
  induced (Li , demeclocycline ), results of
  hypokalemia
• ,hypercalcemia ,
  intrinsic renal disease )
• Reset osmostat
• Skin losses
• Iatrogenic

43
Disorders of Sodium balance hypernatremia

• ECF volume expanded hypervolemic
  hypernatremia gain of water and sodium
• Iatrogenic parenteral administration of
  hypertonic solutions(NaHCO3, saline , medications
  and nutrition )
• Mineralocorticoid excess

44
Disorders of Sodium balance hypernatremia

• Treatment
• Water deficit (L)0.6 x total body weight
  (kg)x(serumNa in mmol/L/140)1
• Rapid correction of hypernatremia can result in
  cerebral edema , permanent neurological damage
• Only one half of the water deficit should be
  corrected over the first 24 hr , with the
  remainder being corrected over the follwing 2
  to 3 days .
• Central diabetes insipidus treated with
  desmopressin acetate administrated intranasally
  0.1 to 0.4 ml daily or subcutaneously or
  intravenously 0.5 to 1 ml daily .

45
Disorders of potassium balance

• Physiology
• K is the major intracellular cation, with only 2
  of total body k located in the extracellular
  space
• The normal serum concentration is 3.3 to 4.9
  mmol/L .
• Approximately 50 to 100 mmol of k is ingested and
  absorbed daily , 90 of k is renally excreted
  with the remainder eliminated in stools.

46
Disorders of potassium balance

• Hyperkalemia
• Plasma K gt 5.5
• Hyperkalemia can result from
• 1- Intercompartment shift of K ions
• in large burns and severe muscle trauma
• acidosis,
• cell lysis following chemotherapy.
• massive tissue trauma
• rhabdomyolysis
• drugs digitalis overdose, B2 adrenergic
  blockage,
• succinylcholine

47
Disorders of potassium balance

• 2. decreased excretion of K
• Renal failure
• K sparing diuretic , Spironolactone.
• ACE inhibitors
• NSAIDs
• Cyclosporin.

48
Disorders of potassium balance

• 3- Increased K intake
• rarely causing hyper K in normal individuals
  unless large amounts are given rapidly by IV.
• K intake increases in patients receiving B
  blockers, RF, insulin deficiency will cause
  hyperkalemia
• Unrecognized sources of K include K
  penicillin, K salts, transfusion of stored whole
  blood ( plasma K in a unit of whole blood can
  increase to 30 mEq/L after 21 days of storage).

49
Disorders of potassium balance
50
Disorders of potassium balance

• Treatment
• Drugs contributing to hyper K should be D/C and
  sources of increased K intake should be stopped.
• If due to hypoaldosteronism, Rx with
  mineralocorticoid replacement.
• Calcium ( 5 10 ml of 10 calcium gluconate or 3
  5 ml of 10 calcium chloride ) partially
  antagonizes the cardiac effects of hyper K is
  useful in marked hyper K ( has rapid but short
  action ).

51
Disorders of potassium balance

• Treatment
• Sodium bicarbonate IV, if metabolic acidosis is
  present.
• B- agonists, in hyper K associated with massive
  transfusions.
• IV infusion of glucose and insulin ( 30 50g of
  glucose per 10 units of insulin) (but often takes
  1 hour to peak effect).
• Furosemide ( in patients with some renal
  function). In the absence of renal function, non
  absorbable cation exchange resin.
• Dialysis ( in symptomatic patients with severe or
  refractory hyper K ).

52
Disorders of potassium balance

• Hypokalemia
• Plasma K lt 3.5 mEq/L.
• Causes
• 1- Intercompartmental shift of K.
• 2- Increased K loss.
• 3- Inadequate K intake.

53
Disorders of potassium balance

• Hypokalemia
• A- Intercompartmental shift of K
• - Due to intracellular movement of K.
• Alkalosis.
• insulin therapy.
• B2 adrenergic agonists.
• hypothermia.
• Vitamin B12 and folate therapy in megaloblastic
  anemia.
• transfusion of frozen red cells ( because these
  cells lose K in the preservation process and
  take up K following reinfusion).

54
Disorders of potassium balance

• Hypokalemia
• B- Increased K losses
• - Renal (urinary K gt 20 mEq/L)
• Diurtic
• mineralocorticoid therapy,
• hypomagnesemia,
• renal tubular acidosis,
• ketoacidosis,
• drugs (amphotericin B).
• - GI (urinary K lt 20 mEq/L)
• vomiting,
• nasogastric suctioning,
• diarrhea,
• losses from fistulae,
• laxative abuse,
• villous adenomas,
• pancreatic tumors secreting VIP.

55
Disorders of potassium balance

• Hypokalemia
• C - Decreased K intake
• - Marked reduction in K intake is required
  to produce hypo K bec.
• Of the kidneys ability to decrease
  urinary excretion to as low as 5-
• 20 mEq/L.

56
Disorders of potassium balance

• Clinical manifestations
• Mild hypokalemia Kgt3 mmol/L is generally
  asymptomatic
• Severe hypokalemia Klt3 mmol/L
• Can produce widespread organs dysfunction
• primarily cardiovascular.
• renal Polyuria ( nephrogenic DI ).
• Increased HCO3 absorption gt hypochloremic
  metabolic
• alkalosis.
• Increased ammonia production.
• chronic hypo K gtgt renal fibrosis.

57
Disorders of potassium balance

• neuromascular.
• Skeletal muscle weakness .
• Muscle cramping.
• ileus.
• Tetany.
• Rhabdomyolysis
• hormonal effect.
• Decreased insulin secretion.
• Decreased aldosterone secretion.
• metabolic.
• - Negative nitrogen balance.
• Encephalopathy ( liver dx.)

58
Disorders of potassium balance

• Hypokalemia
• Clinical manifestations of hypo K
• Cardiovascular
• Abnormal ECG
• T wave flattening inversion.
• Prominent U wave.
• ST segment
  depression.
• increased P wave
  amplitude.
• Prolonged P-R
  interval.
• Arrythmias.
• Decreased contractility.
• Labile BP ( autonomic dysfunction).
• Chronic hypo K gt Myocardic fibrosis

59
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60
Disorders of potassium balance

• The treatment of hypo K depends on the severity
  of any associated organ dysfunction
• Peripheral IV replacement must be lt 8mEq/L ( K
  irritative effects on veins).
• Faster IV replacement ( 10 20 mEq/L)
  requires CVP and ECG monitoring.
• Higher replacement rates safest through
  femoral catheter ( bec very high localized K
  conc. May occur within the heart with CVP).
• IV replacement shouldnt exceed 240mEq/day.

61
Disorders of potassium balance

• KCl is the preferred K salt when metabolic
  alkalosis is present because it corrects the Cl
  deficit also.
• KHCO3 or K acetate or K citrate preferable for
  metabolic acidosis.
• KPO4 suitable in concomitant hypo PO4 (
  diabetic ketoacidosis).
• Dextrose containing solutions must be avoided
  because the resulting hyperglycemia and insulin
  secretion may lower plasma K.

62
Disorders of calcium balance

• Physiology
• Serum calcium 2.23 to 2.57mmol/L
• Exists in three forms
• ionized (45)1.15 to 1.27mmol/L is physiology
  active.
• Protein bound (40).
• Complexed to freely diffusible compounds (15).
• Daily calcium intake ranges from 500 to 1000mg.
• Normal calcium metabolism is under the influence
  of the parathyroid hormone (PTH) and vitamin D .
• PTH promotes calcium resorption from bone and
  reclamation of the calcium from the glomerular
  filtrate.
• Vitamin D increases calcium absorption from the
  intestinal tract

63
Disorders of calcium balance

• hypocalcemia
• Causes
• Increased serum phosphate level
• Chronic renal failure gtgtgtgtgtgtinadequate production
  
• of active vitamin D and renal phosphate
  retenion
• Phosphate therapy.
• Hypoparathyroidism
• Postthyroidectomy and parathyroidectomy .
• Congenital deficiency (DiGeorge syndrome )
• Idiopathic hypoparathyroidism (autoimmune )
• Severe hypomagnesaemia (inhibits PTH release).

64
Disorders of calcium balance

• hypocalcemia
• Causes
• Vitamin D deficiency
• Osteomalacia
• Resistance
• End organ resistance to PTH
• Pseudohypoparathyroidism
• Drugs
• Calcitonin
• Bisphosphanates
• Miscellaneous
• Acute pancreatitis
• Citrated blood in massive transfusion

65
Disorders of calcium balance

• Hypocalcemia
• Clinical manifestations
• Parasthesis.
• confusion.
• Laryngeal stridor ( laryngospasm).
• Carpopedal spasm ( Trousseaus sign).
• Masseter spasm ( Chvosteks sign).
• tetany
• seizures.
• Dysarrythmias, heart failure, hypotension.
• Bronchospasm.
• Biliary colic.
• ECG changes prolongation of QT interval.

66
Disorders of calcium balance

• Hypocalcemia
• What is chvostek s sign ??
• Tapping over the facial nerve in the region of
  the parotid gland causes twitching of facial
  muscles.
• What is the trousseau s sign ??
• carpopedal spasm ( opposition of the thumb,
  extension of the interphalangel and flexion of
  the metacarpophalangeal joints induced by
  inflation of the sphygmomanometer cuff to level
  above systolic blood pressure .

67
Disorders of calcium balance

• Hypocalcemia
• Treatment
• - Symptomatic hypo Ca is a medical emergency
  and must be treated immediately with ca
  bolus
• IV CaCl ( 3-5 ml of 10 solution).
• IV Ca gluconate ( 10 20 ml of 10 solution
  over 10 min ).
• then followed by a maintained infusion of 1-2
  mg /kg elemental calcium /hr for 4 hr .
• Maintenance therapy is with alfacalcidol
  (1a-OH-D3).

68
Disorders of calcium balance

• Hypercalcemia
• Causes
• Excess PTH
• Primary hyperparathyroidism ? a single
  parathyroid gland adenoma , hyperplasia , rarely
  carcinoma
• Tertiary hyperparathyroidism ?parathyroid
  hyperplasia after long standing secondary
  hyperparathyroidism
• Ectopic PTH (very rare)
• Malignant disease
• Multiple myeloma.
• Breast cancer
• Bronchus
• Thyroid

69
Disorders of calcium balance

• Hypercalcemia- causes
• Excess action of vitamin D
• Self administered vitamin D
• Sacroidosis
• Excess calcium intake
• Milk alkali syndrome .
• Other endocrine disease
• Thyrotoxicosis
• addisons disease (hyponatremia ,hyperkalemia,
  hypoglycaemia and hypercalcemia).
• Drugs
• Thiazides
• Lithium
• Vitamin A and retinoic acid
• Others
• Long term immobility
• Familial hypocalciuric hypercalcaemia

70
Disorders of calcium balance

• Hypercalcemia
• Clinical manifestations
• general malaise
• Depression
• Bone pain
• Abdominal pain
• Nausea
• Constipation
• Polyuria ,nocturia-gtgtgtca deposition in renal
  tubules
• Renal stonegtgt renal failure.
• Dehydration
• Confusion
• Risk of cardiac arrest.
• ECG changes short ST segment, short QT interval.

71
Disorders of calcium balance

• Hypercalcemia
• Investigation
• serum ca and phosphate gtgtgtlow phospahate
  gtprimary hyperparathyrodism ,
• PTH .
• Radiology subperiosteal erosions in the
  phalanges gtgthyperparathyroidism .
• Protein electrophoresis for myeloma
• TSH to exclude hyperthyroidism
• Synacthen test to exclude addisons dx.
• Hydrocortisone suppression test lead to
  suppression of plasma calcium in sarcoidosis,
  vitamin D mediated hypercalcemia.

72
Disorders of calcium balance

• Hypercalcemia
• Management of severe hypercalcemia
• Rehydration with intravenous fluid (0.9 saline
  )
• 4-6 L of IV saline over 24 h and then 3-4Lfor
  several days .
• after minimum of 2 L of IVF give
  bisphosphonate infusion.
• Prednisolone (30-60 mg daily )gtgtfor myeloma,
  sarcoidosis and vitamin D excess
• Dialysis ( in renal or cardiac failure).
• Treat the underlying pathology.

73
Disorders of Phosphorus balance

• Hyperphosphatemia
• If phosphate level more than 1.5 mmol/L
• Causes
• Increased intake ( abuse of phosphate laxatives,
  Excessive
• KPO4 administration).
• Decreased excretion ( Renal insuffeciency).
• Massive cell lysis ( following chemotherapy for
  lymphoma
• or leukemia).
• Clinical manifestations
• Marked hyper PO4 decreases plasma Ca by
  precipitation
• and deposition of CaPo4 in bone and
  soft tissues.
• Treatment
• Phosphate binding antacids ( Aluminum hydroxide
  or
• carbonate).
• note phosphate level 0.8-1.5 mmol/l

74
Disorders of Phosphorus balance

• Hypophosphatemia
• Causes
• redistrubitionof phosphate from extracellular
  fluid into cell
• treatment of diabetic ketoacidosis .
• Refeeding syndrome .
• Acute respiratory alkalosis .
• Hungry bone syndrome after parathyroidectomy .
• decreased intestinal absorption
• poor oral intake
• Some antiacid
• Diarrhea
• Increased urine excretion
• Hyperparathyrodism
• Vitamin D deficicency
• Primary renal abnormality

75
Disorders of Phosphorus balance

• Hypophosphatemia
• If phosphate level lt0.8 mmol/l
• Clinical manifestations
• Severe hypophosphatenemia cause widespread
  organ dysfunction
• Cardiomyopathy.
• Impaired O2 delivery.
• Hemolysis.
• Impaired leukocyte function.
• Platelets dysfunction.
• Encephalopathy.
• Skeletal myopathy.
• Respiratory failure.
• Rhabdomyolysis.
• Hepatic dysfunction.

76
Disorders of Phosphorus balance

• Hypophosphatemia
• Treatment
• Oral PO4 replacement .
• IV KPO4 or NaPO4 ( 2-5 mg of PO4/Kg or 10
  45
• mmol slowly over 6-12 hrs ).
• Note Oral replacement is generally
  preferable to IV because risk of
  hypocalcemia and metastatic calcification.

77
Disorders of Magnesium balance

• Hypermagnesemia
• Causes
• Excessive intake ( Mg containing antacids or
  laxatives).
• Renal impairment.
• Iatrogenic ( Mg sulfate Rx for gestational
  HTN).
• adrenal insufficiency.
• Hypothyroidism.
• Rhabdomyolysis.
• Lithium Rx.

78
Disorders of Magnesium balance

• Hypermagnesemia
• Clinical manifestations
• neurological sedative with Hyporeflexia.
• Skeletal muscle weakness.
• cardiovascular system myocardial depression
  with hypotension and cardiac
  conduction defect .
• gtgt.gtgt ECG changes Prolonged PR interval,
  widening QRS
• complex.
• Respiratory arrest ( in severe hyper Mg).

79
Disorders of Magnesium balance

• Hypermagnesemia
• Treatment
• Stop All sources of Mg intake.
• IV calcium ( 1 gm calcium gluconate).
• Loop diuretic infusion of ½ NS in 5 Dx.
• Dialysis ( in severe cases).

80
Disorders of Magnesium balance

• Hypomagnesemia
• If Mglt0.7 mmol/L
• Associated with other deficiencies like K, PO4
• Causes
• Inadequate intake .
• Reduced GI absorption ( malabsorption syndromes,
  severe diarrhea, prolonged NGT).
• Increased renal excretion ( Diuresis, Diabetic
  ketoacidosis, Hypophosphatemia ,
  Hyperparathyroidism).
• Drugs ( Ethanol, Diuretics, theophyllins,
  Aminoglycosides,
• Cisplatin, Cyclosporin, Amphotericin
  B).

81
Disorders of Magnesium balance

• Hypomagnesemia
• hypomagnesemia increases renal excreation of k
  and inhibits secretion of parathyroid hormone and
  leads to parathyroid resistance , so many of
  symptoms of hypomagnesaemia are due to
  hypokalemia and hypocalcemia .

82
Disorders of Magnesium balance

• Hypomagnesemia
• Clinical manifestations
• Anorexia.
• Weakness.
• Fasciculation.
• parasthesis.
• Confusion.
• Ataxia.
• Seizures.
• Cardiac potentiation of digoxin toxicity
• (aggrevated by hypo K ), AF.
• ECG prolongation of PR and QT intervals.

83
Disorders of Magnesium balance

• Hypomagnesemia
• Treatment
• oral supplements (magnesium chloride 5-20mmol
  OD or magnesium oxide tablets 600mg four times
  daily ).
• If seizures or ventricular arrhythmias gtgtgtIV
  infusion
• (50mmol of MgCl in 1L of 5 dextrose over
  12-24 h)
• plus a loading dose (4 mmol over 10 min ).

84

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